[CodeGen] Use StringRef. NFC.

Looks like CurFn's name outlives FunctionName, so we can just pass
StringRefs around rather than going from a StringRef to a std::string
to a const char* to a StringRef.

llvm-svn: 285873
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index bdd2026..7def774 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -773,7 +773,7 @@
   llvm::Type *getGenericBlockLiteralType();
 
   /// Gets the address of a block which requires no captures.
-  llvm::Constant *GetAddrOfGlobalBlock(const BlockExpr *BE, const char *);
+  llvm::Constant *GetAddrOfGlobalBlock(const BlockExpr *BE, StringRef Name);
   
   /// Return a pointer to a constant CFString object for the given string.
   ConstantAddress GetAddrOfConstantCFString(const StringLiteral *Literal);